Whole roasted onions are soft, aromatic, and so delicious that they become a stand-alone side dish! This recipe and these tips will give you the perfect baked onion every single time.
Here’s how this is going to go down, my friends: whole roasted onions, roasted with olive oil and butter, roasted with rosemary, roasted whole, roasted to sweet submission.
It’s cold. I mean… really cold. Here’s our chance to crank up the oven, throw these onions inside and lean against the oven door as they transform from sharp and bitey to soft and sweet! And while we’re at it, here’s how to roast any vegetable.
Oh, wait… you might be one of those people who think they don’t like onions. I’m here to tell you that you’re wrong. You exclusively like whole roasted onions, especially these.
And, if you’re feeling fancy, you might want to try this recipe for Ottolenghi’s Miso Butter Roasted Onions and Garlic! It’s like a savory onion candy.
What are roasted onions?
This recipe is just like it sounds. You season and bake whole onions with slices of real butter on top. Roasting them softens the onions and brings out their natural sweetness.
If you aren’t a fan of the sharp flavor of onions, roasting them cuts the boldness back and makes them easier on your palette. And the butter, well… what doesn’t butter do?
Best types of onions to bake
When it comes to roasting or baking onions, use:
- White onions
- Yellow onions
They hold their shape and texture the best. Plus, both types have a strong flavor that sweetens magnificently when you bake them.
The best tips for making oven-roasted onions
The best thing about cooking is how much control you have over the way your food turns out! If you change my recipe, let me know. I’d love to hear what you did (and who knows… maybe I’ll try it that way?).
- Quarter or slice the onions first. The smaller the onions are, the quicker they will bake, so keep an eye on the oven. It will also allow the butter and seasonings to go deep into the onion and become even MORE flavorful.
- Fresh rosemary is the best herb to roast with onions, but try it with fresh sprigs of thyme. Its sweet earthiness can really bring out the buttery notes in the onions.
- Drizzle balsamic vinegar on top of the onions right before you bake them. As the onions caramelize, the vinegar will break the onions down even more and release more sugar (what more could you want?), giving you tangy-sweet onions in the end.
How to roast an onion in the air fryer
Roasting is magic. It’s as simple as that, but you don’t have to heat up the entire kitchen just to roast a few onions (I’m looking at you, summertime humidity).
To roast onions in the air fryer, follow the same instructions in the recipe card!
Place the onions in the air fryer basket. Set it to 375°F and air fry them for 20 minutes. If they aren’t done to your liking, roast for another 10 minutes.
Serve and enjoy
These roasted onions – tops removed and toasted in their jackets – become soft, smooth, sweet, and almost spreadable.
The best way to eat a roasted onion is to slice it and eat it as a side dish along with a juicy pork chop and some fluffy mashed potatoes. Or, you could roast the onions and add a few slices on top of some baked sweet potatoes or on top of your favorite salad for a healthier option – if you’re a fan of that kind of thing.
How to store leftovers
Honestly, whole roasted onions taste the best when they are fresh out of the oven. You can store leftovers in an airtight container in the refrigerator for up to three days.
Just know that they will become softer, and their flavor will change. It just isn’t the same. Eat them fresh, trust me!
I hope you enjoy this recipe. Leave me a comment down below on how you plan to serve these roasted onions. I wanna know!
You might also enjoy these Miso Butter Roasted Onions!Print
Whole Roasted Onions
- Prep Time: 10
- Cook Time: 45
- Total Time: 55 minutes
- 9 small and medium yellow onions
- 1/4 cup olive oil
- 2 tablespoons unsalted butter, thinly sliced
- coarse sea salt
- fresh cracked black pepper
- fresh rosemary sprigs
- Place a rack in the upper third of the oven and preheat oven to 375 degrees F.
- Cut the tops off of each onion, but leave most of the skins on the onion.
- Arrange the onions in a square baking dish or a rimmed sheet pan.
- Drizzle the olive oil over the onions. Place a thin pat of butter on each onion.
- Sprinkle generously with salt and pepper and top with a rosemary sprig.
- Bake for 25 minutes until bubbling and tender.
- Increase the oven temperature to 400 degrees F and cook for another 15 to 20 minutes until the onions are completely tender and the tops are browned.
- Remove from the oven and allow to cool slightly.
- Remove the skins, slice and enjoy warm.
they do freeze beautifully! theres 4 of us I made a whole tray full and froze them in 4s, reheated in oven after defrosting and delicious. perfect for a huge sack. I also slice about 5 kg and put them in the slow cooker for a day with butter olive oil and black pepper then portion them up to freeze. caramalised onions whenever I need them
I Wonder if they’d freeze?
i don’t think so.
try boiling them, taking off skins, cut in half placein dish cover with heavy cream and parmesan cheese then bake .wow
Trim a little bit off the root end so that you have a flat spot for them to sit level. After you brown them on the top, flip them over for the bottom to brown, as the browned parts are the very sweetest.
You truly are a master at living.
Oh I bet this would make the best garlic-y onion bread!! Roasted onion and garlic.. Holy moly! Thank you for sharing this idea and kicking my imagination into gear! I love some of the other commenter’s ideas too! Baked potatoes! NICE.
The Queen of Dreaming
Oh I love roasted onions so much! I’ve never tried to add butter, next time I’ll do!
LEE @ Modern Granola
I’ve never done this before! It looks amazing. Will give this a shot soon!
I second the comment for wanting to know how you cook thin pork chops without them tasting over dry! Pretty please tell us??
Quickly fry them on a high heat with some oil. Colour both sides then, take off the heat, cover in foil and stand for a couple of minutes to finish cooking without burning. If they were fatter pork steaks, I’d do the same but put in the oven at around 150C to finish cooking.
yumm! just baked at 30 minutes at 375 and 50 minutes at 400, could have used more time but i was impatient : )
Ha! I love these onions! I make them every year for Thanksgiving! Somehow I always improve them and this year it is going to be by keeping the skins on in 2015!
Below is my version.
I love it when you post a recipe I have all the ingredients for on hand AND it fits into my pre-existing dinner plan.
They tasted like roasted onions you might have had in a root vegetable medly. I was hoping they would become creamier than normal roasted onions, more like roasted garlic, but alas no. They were pretty.
Also I was impatient and they were too hot to slice thin, so I just cut one in half and put it on the dinner plate with some coleslaw, roasted butternut and hamburgers. I roasted the onions in the same oven as the squash so they were easy to make.
Whole Roasted Onions were not bad, but not as special as they look. #my2cents
Made these for dinner last night (served them with sausage, etc.) Very yummy. Will make again!
This post made me laugh out loud, and my mouth water. Pork and onions is ALWAYS a winning combo!
Tried them last night with my beef roast. Wonderful.